The following are the first four terms of a sequence: a, a (1/b),a(1/b(1/b),a(1/b)(1/b)(1/b)

Question

where a is a positive integer. Is the eight term positive or negative? explain

So the sequence could be seen as
{a/b^(n-1): n=1,2,3...}
I hope you can see that the sign of each term will depend on the sign of b. If b is negative, then the signs for the terms will alternate.
You should also see that the odd terms of the sequence have b to an even power and the even ones have it to and odd power. Thus the answer would be whatever the sign of b is for the 8-th term. Does this make sense?

please could u tell me the nth term to term rule in 0,1,3,6,10,15,21

Thank very much